Broken Symmetry and Spacetime

Abstract

The phenomenon of broken spacetime symmetry in the quantum theory of infinite systems seems to point toward an unorthodox ontology. The standard conception of the physical meaning of these symmetries, as changes in coordinates, conflicts with the apparent physical inequivalence of symmetry-related states. I argue that this apparent conflict is an artifact a subtle error in the extant account of physical equivalence due to Halvorson and Clifton.